The present invention, in some embodiments thereof, relates to the use of tolerance inducing anti-third party cytotoxic T-lymphocytes (CTLs), capable of preventing or ameliorating immune rejection of donor cells without inducing graft versus host disease (GVHD), in adoptive cellular therapy.
Adoptive immunotherapies have been employed in which therapeutic lymphocytes (e.g. T cells) are administered to patients in order to treat viral infection or cancer. Examples of such immunotherapies include the graft versus leukemia (GVL) effect mediated by donor lymphocyte infusion (DLI) for treatment of hematopoietic cancer after allogeneic stem cell transplantation. An additional example includes the therapeutic infusion of ex-vivo expanded tumor infiltrating lymphocytes (TIL) in combination with lymphodepletion for the treatment of melanoma [Fujiwara H., Pharmaceuticals (2014) 7: 1049-1068].
Despite these successes, both DLI and TIL therapies have major drawbacks, DLI is usually associated with graft versus host disease (GVHD) while preparation of TIL for therapy is time and labor consuming and not always successful. The main challenge remains separation of the GVL effect from GVHD. Thus, currently most therapeutics employ autologous or HLA-identical cells.
Previous studies have substantiated that hematopoietic stem cells, namely, cells within the CD34+ fraction, are endowed with veto activity (e.g. donor cells which lead to apoptosis of host cells upon contact with same), thereby allowing them to induce tolerance when administered to hosts at high numbers i.e. “megadose” transplants [Gur et al., Blood (2005) 105:2585-2593; Gur et al., Blood (2002) 99:4174-4181; Rachamim et al., Transplantation (1998) 65:1386-1393]. However, the amount of CD34+ cells that can be harvested in humans is usually insufficient for achieving tolerance under reduced intensity conditioning protocols (RIC).
Other cell types have also been shown to mediate veto activity including T lymphocytes (e.g. CD8+ CTLs), natural killer cells and dendritic cells. Direct comparison of the veto activity of various cell types revealed that cytotoxic T lymphocytes (CTLs) comprise the strongest veto effect [Reich-Zeliger et al., J Immunol. (2004) 173:6654-6659].
One approach developed to generate veto CTLs devoid of graft versus host (GVH) activity was described by Reisner and co-workers, in which CTLs were stimulated against 3rd-party stimulators in the absence of exogenous IL-2. This approach was based on the observation that only activated cytotoxic T lymphocyte precursors (CTLp) were capable of surviving the IL-2 deprivation in the primary culture (IL-2 starvation results in apoptosis of non-induced T cells). This method was shown in vitro and in vivo to deplete GVH reactivity from the anti-3rd party veto CTLs [PCT Publication No. WO 2001/049243, Bachar-Lustig et al., Blood. 2003; 102:1943-1950; Aviner et al., Hum Immunol. (2005) 66:644-652]. Introduction of these anti-3rd party veto CTLs into a recipient (along with a transplant) prevented graft rejection without inducing graft versus host disease (GVHD) (PCT Publication No. WO 2001/049243).
Various approaches have been contemplated for generation of tolerance inducing cells devoid of GVH reactivity and the use of same as an adjuvant treatment for graft transplantation, some are summarized infra.
PCT Publication No. WO 2007/023491 discloses the use of tolerogenic cells for reducing or preventing graft rejection of a non-syngeneic graft in a subject. The tolerogenic T regulatory cells disclosed (e.g. CD4+CD25+ cells) may be derived from any donor who is non-syngeneic with both the subject and the graft (“third-party” tolerogenic cells). The graft (e.g. bone marrow) may be derived from any graft donor who is allogeneic or xenogeneic with the subject.
PCT Publication No. WO 2002/102971 discloses the use of cultured hematopoietic progenitor cells (HPC) comprising enhanced veto activity for inducing tolerance to a transplant transplanted from a donor to a recipient. The tolerogenic cells disclosed preferably express CD33 and are administered prior to, concomitantly with or following transplantation of the transplant (e.g. cell or organ transplant).
PCT Publication No. WO 2010/049935 discloses an isolated population of cells comprising non-GVHD inducing anti-third party cells having a central memory T-lymphocyte (Tcm) phenotype, the cells being tolerance-inducing cells and capable of homing to the lymph nodes following transplantation. Specifically, WO 2010/049935 teaches co-transplantation of immature hematopoietic stem cells along with the anti-third party Tcm cells. The use of the anti-third party Tcm cells enabled engraftment of immature hematopoietic cells without graft versus host disease (GVHD).
PCT Publication No. WO 2013/035099 discloses methods of generating an isolated population of cells comprising anti-third party cells having central memory a T-lymphocyte (Tcm) phenotype, the cells being tolerance-inducing cells and/or endowed with anti-disease activity, and capable of homing to the lymph nodes following transplantation.